ABSTRACT For the past 15 years, we have chronicled the development of over 600 primarily low-income, first- generation Latino children born in the Salinas Valley, known as ?the nation's salad bowl.? The children of the CHAMACOS longitudinal birth cohort are now coming of age in a community identified by the Department of Justice as an epicenter of youth gang violence. Our previous research has shown that in utero exposure to organophosphate pesticides (OPs) was associated with impaired attention3 and lower IQ at school age for CHAMACOS children,4 both of which are risk factors for adverse behavioral outcomes in adolescence and adulthood. Our data also indicate that CHAMACOS children have experienced considerable early life stressors, including poverty, food insecurity, housing instability, household overcrowding, family conflict and separation, maternal depression, and fear of deportation that may predispose them to adverse outcomes. We propose to investigate the interaction of in utero exposure to a host of neurotoxic pesticides with early life social adversity in association with behavioral outcomes during the transition from adolescence to early adulthood (age 16 and ~18 years): specifically, externalizing and risk-taking behaviors, delinquent and criminal activities, and school failure versus success/graduation. Through our research, we will investigate developmental outcomes of exposure to the complex mixture of pesticides used in Salinas Valley agriculture, making use of geo-coded that allows assessment of chemicals that lack biomarkers. We will also collaborate with child development Pesticide Use Reporting data (PUR) experts to synthesize the wealth of data we have gathered on family-level and neighborhood-level adversities (e.g. poverty, crime) into cumulative adversity exposure variables corresponding to specific developmental windows (i.e. in utero, birth to age 5, and birth to age 9), and will do the same for protective factors (e.g. maintenance of positive cultural values, child-parent attachment). We hypothesize that exposure to neurotoxic pesticides and early life adversity will each independently increase adverse behavioral outcomes in adolescence/early adulthood, and that early adversity may modify the effects of pesticide exposures. We further suggest that the decreased cognitive abilities and poorer attention observed in association with pesticide exposure in CHAMACOS children at school age may mediate this relationship. Thus, the goal of this project is to evaluate the neurotoxicity of current-use pesticides and early social adversity to human populations, assess effects of early life exposure to both these chemical and non-chemical stressors on adolescent/early adult behaviors of societal concern, and identify targets for early intervention to prevent longer term poor outcomes.